1. Technical Field
The present invention relates to a light source unit, an illumination device, an image display apparatus, and a monitor apparatus, and specifically, to a laser light source unit technology of supplying laser light.
2. Related Art
Recently, as a light source unit for a projector, a technology using a laser light source that supplies laser light has been proposed. As a laser light source, not only one that directly supplies fundamental wave light from a light emitting part but also one that converts the wavelength of the fundamental wave light and supplies it is known. As a wavelength conversion element that converts the wavelength of fundamental wave light, for example, a second-harmonic generation (SHG) element is used. As the SHG element, for example, a nonlinear optical crystal is used. Within the nonlinear optical crystal that performs second harmonic generation, nonlinearly-polarized wave and SHG wave propagate because of nonlinear polarization induced by a strong photoelectric field. The SHG element can generate SHG wave efficiently when the phase matching condition depending on generation wavelength or the like is satisfied. Phase matching refers to matching of phases between the nonlinearly-polarized wave and SHG wave. Phase matching includes angular phase matching of entering the fundamental wave at an incident angle at which the refractive index at the wavelength of the fundamental wave and the refractive index at the wavelength of the SHG wave are equal, for example. In a related art, a technology of adjusting the phase matching angle has been proposed for efficient SHG wave generation (e.g., see JP-A-2000-250082). The phase matching angle refers to the incident angle of the fundamental wave that satisfies the phase matching condition.